Make sure that on altatennis.org your are on the “designees” tab for your team — sounds like you are trying to add TennisPoint as a player instead. Here are the steps for adding TennisPoint as a designee: http://www.tennispoint.com/?event=altaDesignee
FYI, when you search and find TennisPoint’s account
→ name is “TennisPoint Member”. Ignore the stuff about the “womens St Marlo” team in there where someone a couple of years ago added TennisPoint as a player. On the designee tab you shouldn’t get any warnings at all - none about men/women nor about non-paid either (designee accounts are free accounts since they are for coaches, clubs, etc).