If you want to play safe, uninstall the plug-in, delete its source. Upgrade Moodle and then install the matching version of the plug-in.
Why do you go for 3.6? The current stable is 3.7. Don't have PHP 7.1? If it is the case you might want to go for the Release 3.5 (LTS), which is supported 12 months longer.
Why do you go for 3.6? The current stable is 3.7. Don't have PHP 7.1? If it is the case you might want to go for the Release 3.5 (LTS), which is supported 12 months longer.