While I agree with the general premise that you get free-archetype feats all the way up, and (absent a campaign-specific restriction to the contrary) they can be from any combination of archetypes (subject to the usual requirement to take two feats before the next Dedication - again unless waived), I do not think that that bit is saying what you think it is saying.
"If the group all has the same archetype or draws from a limited list, you might want to ignore the free archetype’s normal restriction of selecting a certain number of feats before taking a new archetype. That way a character can still pursue another archetype that also fits their character." (Emphasis mine.)
What it says to me is that, if you are using the variant with a specific mandated archetype in the extra slots, you might allow the PC to take a second archetype
alongside it in their normal rather than having to wait until they are three feats in.