Use our tried and tested CTRL J method. Save yourself from the headache trying to figure out how to get playstore to work. Unless you know how rip, mod and rebuild a rom, I would not advise it. There's no real need to add playstore and the bulk of google stuff that comes with on such a low powered box.
I've already given up on Kodi. Too much hassle for so little. Now I just stick to standalone apps for streaming. Among others :
Morpheus TV
ShowBox
MegaBox
Popcorn Time
Kshow
Viu
Animania
RedBox TV
LiveNet
Mobdro
RSSPlayer
For everything else in between there's always a streaming site somewhere to use with firefox

Oh, btw, I have all this loaded on my main droid box. There's no way the tm stb can handle so many apps without crapping itself. Just install what you need. I'd recommend morpheus tv first.