AffiliateWP supports the same environment WordPress itself recommends: the latest version of WordPress, and PHP 8 or newer. Every official addon has the same requirements.
AffiliateWP may still run on older versions, but new releases are built and tested against the versions WordPress recommends, so an out-of-date stack is the first thing to rule out when something misbehaves.
An individual addon release may also need a recent version of AffiliateWP itself, so keep AffiliateWP up to date alongside its addons.
To see the versions your site runs, go to AffiliateWP » Tools » System Info, or WordPress’s own report at Tools » Site Health » Info.