What's the adjective for volunteers? Here's the word you're looking for.
Included below are past participle and present participle forms for the
verbs volunteer and voluntell which may be used as adjectives within certain contexts.
“The dominant mode of functioning was volunteeristic and supportive of current practice, but activists could carve out space for their agendas within the limits of the forum.”
“By some accounts, in fact, those who had planted gardens sometimes confronted an excessive amount of volunteered help from people who had not planted gardens of their own.”