Files taking up too much storage - I cannot export now

I'm working on a video for my youtube channel since a week, while editing the video the app keep crashing but still I keep the patience and work on different projects to complete the video.

Now comes the worst thing I had experienced, while exporting it crash again and it keep taking the storage in my Ipad air. Now I'm not able to export the video I'm working since a week. Well FYI I'm exporting in 4K.

Then I seach online and find out that I can sync my project and then can export it from laptop. First I sync my project and then when I install the software in my laptop and sign in with the same account then I experienced the second worst thing. It says that I need to buy this product again on my laptop now.

Is it my fault if your app is not working properly on my iPad Air? I trust on you and now you want me to spend more money to buy it for laptop. What is the assurance that it will work fine on laptop?

I'm also attaching the log files.

I hope you will solve my issue and reply to me ASAP.