As an association, you should always check what is stated in your association's bylaws regarding how many members should be in your board. It is important that there is consistency between what is written in your bylaws and what is indicated in the submission to the financial institution.
No bylaws
If the association is in the process of creating or changing its bylaws and seeks advice on how many board members to state, you can consider reaching out to similar associations to ask how many board members are typically in boards for your type of association. The most common number is 4-8 members.
By definition, there must be at least two members on a board, as an association is about a community. In Unioo, you can register a maximum of 40 members.