Hey Gregory,
the Flowline Placid does fit on the Easyrig Minimax, but you have to drill a hole through the top for the string yourself. I haven't used this combo myself yet tho, as I held out buying the Flowline Placid, due to there beeing little to no information out there on how well it works when using it with a Gimbal. If you end up getting it, I would be very curious how well it works!