I try to link it this way, but the following message appears
"The operation cannot be completed: An FSM project must be billed at task rate or employee rate."

It's because your project is a Field service Project.
check the constraint in python to see the related conditions for that message:

('fsm_imply_task_rate', "CHECK((is_fsm = 't' AND sale_line_id IS NULL) OR (is_fsm = 'f'))", 'An FSM project must be billed at task rate or employee rate.'),

Thank you for replying, it is Done

HI, I am not getting the "invoicing tab" under project even though the billable option is enabled.
V16