Error "Files not on client"

Hey there! I want to setup my FMOD project with our Perforce and followed the documentation for that. in 13.1.1 under 7. it says "Select “File > Source Control > Sync Latest, Merge, and Commit…” but when I do that I get the following error message: C:/Game/Content/FMODproject/game.fspro - file(s) not on client. The documentation doesn´t mention this potential error and I couldn´t find anything on the internet about it. Any ideas?
Thanks in advance! we are on FMOD 2.02.11 (windows 64bit)