If you are a well-seasoned musician, you are probably aware that somewhere north of 85% of working musicians (pro and semi-pro) use Apple computing products for music based tasks. There are lots of reasons for this, some of them good. I do understand it's expensive, but since most Apple products have a longer useful life than PC or Android devices, the higher initial cost is spread over a longer period, and average yearly cost might be less. So maybe do not completely discount them.
If all you need to do is find backing tracks, then YouTube is your friend. There are gazillions of them, many of them quite good.
If you need to CREATE backing tracks, then you need a couple of things - firstly, a DAW (Digital Audio Workstation), a computer program for creating music tracks; you will also likely need a MIDI keyboard. These are available for both Windows and Mac machines, with some available on IOS for iPads and a few less available for Android tablets.
Programs like iRealPro and Band-in-a-Box let you create backing tracks in pre-programmed "styles", which if you need to tweak you can export and edit in a DAW. For RnB you will probably have more success with Band-in-a-Box, it has a wider selection of style libraries. TomPlay, by my understanding, requires the purchase of individual songs; it's really designed as a practice platform, not a backing track generator.
Hope this helps, please reach out if you need further help; there are lots of folks here who are comfortable with computer or tablet based music creation and playback. Maybe start a new thread with your questions.