What fop2admin version do you have installed? Did you try with the latest version?
If you need to do a manual config, you are free to do so by editing fop2.cfg accordingly. You can disable the autoconfiguration by removing the last #exec line and then writing your own user lines and buttonfile=xxxxx on fop2.cfg
For a quick way to get the button config from the autoconfig in a static file, you can run
/usr/local/fop2/autoconfig-users-freepbx.sh > /usr/local/fop2/buttons.cfg
Then in fop2.cfg remove the last #exec line and put instead
user=100:1234:all
buttonfile=buttons.cfg
In any case, your issue might probably be fixed by using the latest fop2admin
Best regards,