I wouldn't mod that pad. Tape it to the floor with some floor mat tape: https://www.amazon.com/gp/product/B07PMLCRHS/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

And play for awhile. Give it a couple of months and see if its something you do regularly and enjoy long term. I've introduced many people to DDR who love it for awhile and bounce off pretty quickly.

If the pad is too shitty to have fun on, and you still aren't sure, there are still zip-up foam style pads in the $40ish range which are leagues better than the one you bought without commiting to the storage, maintenance, cost, and noise of a metal pad.

Another thing I often recommend to folks who haven't played other rhythm games -- play with a controller, too. Rhythm games are addicting as hell but I find that I have to get over an initial skill hump every time I pick one up before the addiction sets in. Doing that with DDR is a bit harder due to the physical component.

Lastly, since you are completely new -- before you dive into DDR you may want to see if PIU is more up your alley. If I was starting over, I would probably have chosen PIU instead. They both have great and active communities.