Many of the big bike shops here do rentals and have their own riding groups that you can join. When I first got my license I went riding with these guys a few times, and they were very friendly and accommodating to a newbie: https://goo.gl/maps/BPCy1us5GkJQ2zMX8
My regular shop in Nangang have a club, though I’ve never gone out with them: https://goo.gl/maps/PeTK9DbY2s5vYNSZ6
And I’ve heard good things about Motor Town: https://goo.gl/maps/TjpDyupD4g33dhT16
You’ll probably also be bombarded with fliers from shops and clubs on test day at whatever riding school you go to for the license (which, if you haven’t done it already, is now ridiculously easy).