I use Wilcom true sizer or stitch era, these work for me oops sorry maybe i am wrong

Rar is a zipped file, you will need to unzip first, then you will find the formats

I use embird to convert rar file to jef ,
dont have any problems.

Here is a discussion with some links. I have 7zip which is now in my right click menu. It gives choices as to where you want to put the files, I choose to unload it to the same folder. When that happens, I delete the rar file. Very easy. Then use software to convert to JEF.