To be more clear this is from the Strike.me FAQ

"No fee DCA

Bitcoin trading fees don’t apply to recurring purchases (aka "DCA") after the first week for hourly and daily purchases, or starting with the 2nd purchase for weekly and monthly purchases."

As to doing it, open Strike, click on Bitcoin and set up a recurring buy at the amount and frequency you want. I do plan on doing some videos on this stuff soon, but don't wait. If you can get on Nostr you can do this, it is a LOT simpler.