i have the same problem. 
i use docker compose to build odoo.

services:

# ODOO

  odoo:

    container_name: odoo

    image: odoo:latest

    depends_on:

      - db

    ports:

      - "xxxx:xxxx"

    volumes:

      - odoo-web-data:/var/lib/odoo

      - ./config:/etc/odoo

      - ./addons:/mnt/extra-addons

      - ./custom_addons:/mnt/custom-addons

    environment:

      - PASSWORD_FILE=/run/secrets/postgresql_password

    secrets:

      - postgresql_password

  db:

    container_name: odoo_db

    image: postgres:15

    environment:

      - POSTGRES_DB=postgres

      - POSTGRES_PASSWORD_FILE=/run/secrets/postgresql_password

      - POSTGRES_USER=odoo

      - PGDATA=/var/lib/postgresql/data/pgdata

    volumes:

      - odoo-db-data:/var/lib/postgresql/data/pgdata

    secrets:

      - postgresql_password

# Segreti

secrets:

  postgresql_password:

    file: odoo_pg_pass

volumes:

  odoo-web-data:

  odoo-db-data:

the file odoo.conf:

[options]

addons_path = /mnt/extra-addons,/mnt/custom-addons

data_dir = /var/lib/odoo

; admin_passwd = admin

; csv_internal_sep = ,

; db_maxconn = 64

; db_name = False

; db_template = template1

; dbfilter = .*

; debug_mode = False

; email_from = False

; limit_memory_hard = 2684354560

; limit_memory_soft = 2147483648

; limit_request = 8192

; limit_time_cpu = 60

; limit_time_real = 120

; list_db = True

; log_db = False

; log_handler = [':INFO']

; log_level = info

; logfile = None

; longpolling_port = 8072

; max_cron_threads = 2

; osv_memory_age_limit = 1.0

; osv_memory_count_limit = False

; smtp_password = False

; smtp_port = 25

; smtp_server = localhost

; smtp_ssl = False

; smtp_user = False

; workers = 0

; xmlrpc = True

; xmlrpc_interface =

; xmlrpc_port = 8069

; xmlrpcs = True

; xmlrpcs_interface =

; xmlrpcs_port = 8071

|-- addons

|-- config

|   `-- odoo.conf

|-- custom_addons

|     |-- accounting_pdf_reports

|     |-- om_account_accountant

|     |-- om_account_asset

|     |-- om_account_budget

|     |-- om_account_daily_reports

|     |-- om_account_followup

|     |-- om_fiscal_year

|     `-- om_recurring_payments

|-- docker-compose.yml

`-- odoo_pg_pass
every time i make a change i restart odoo and odoo_db containers and click the button to update the app list.

Hello everyone,
Thanks for your replies:
I created a new folder "ODOO-ADDSON" in the odoo:\Server\, and I added all the add-ons found in the downloaded of "Odoo 18 Accounting Community" module. I modified the odoo config file and added the path to the add-ons like this:"addons_path = c:\program files\odoo 18.0.20250722\server\odoo\addons,c:\program files\odoo 18.0.20250722\server\ODOO-ADDSON"
 Then I restarted the odoo service on Windows and logged back into the system. I already have developer mode enabled. I updated the application list, but I can't find anything. I even checked that the adds-on directory name matches the name that exists in the "manifest" file of every addson:{
    'name': 'om_account_asset',
    'version': '1.0.0',
    'author': 'Odoo Mates, Odoo SA',
    'depends': ['account'],
    'installable':True,
    'application':True,

I verified the security acces of all directories and its full controle

But i find nothing.

Hi,

When you download a free module like "Odoo 18 Accounting Community" and want to install it, placing it directly in the default Odoo add-ons folder (like C:\Program Files\Odoo\server\odoo\addons) is not recommended, as this directory is managed by Odoo and may be overwritten during updates. Instead, it's better to create a separate custom add-ons folder—for example, C:\odoo_custom_addons\—and move your unzipped module folder into it. After that, go to your Odoo configuration file (usually odoo.conf) and add this new path to the addons_path entry, separating multiple paths with commas. Then restart the Odoo server. Make sure the folder name of the module matches the module's name in its __manifest__.py file. Once done, enable developer mode, go to Apps, and click "Update Apps List" (you may need to enable the option in the debug menu). After updating, search for the module name, and it should appear for installation.

For more details, please refer to the following links:

1. https://www.youtube.com/watch?v=o7L6kSBa_t4

2. https://www.cybrosys.com/odoo/odoo-books/odoo-16-development/setup-development-environment/adding-installing-new-addons/

Hope it helps.

Hi,

have you tried to restart your server?

When you activate developer mode you can also refresh the list by clicking "Update Apps List" at the top.