Can't replace minecraft realm world

Due to lockdown where i live, and my friend's birthday coming up, i figured me and some other friends would build a birthday party for her. it took almost 2 months, but we finished. and i used some minecraft addons in the process. (playing minecraft windows 10 edition btw) so, i exported the world and wanted to make it into a realm, due to the 5 player limit. so i bought the 10 player realm, and i went to the world that i built on, and clicked "play on realm" thinking it would turn the world into a realm, it didn't. i joined the realm and it was a completely different world, different seed and everything, without any of the mods that i used on the world being active, so i clicked "replace world" and added the world that i wanted to add, but it got stuck on this part. 
I tried over 10 times and it still kept getting stuck on this exact same part. i even put the addons in, and it crashed every single time i tried. which is unusal since my computer is not low-ended.
I need help with URGENTLY. this could ruin almost 2 months worth of hard work, and i need it to be fixed by may 26th.