The first error message is the standard message Anaplan returns, due to the import increasing model size to the point where there isn't enough workspace to allow for growth. Either free up workspace to allow for this growth, or analyze models for size reduction opportunities (I'm assuming you're already on the lookout for size optimization opportunties all the time, that's why I list it 2nd).
The 2nd error message is a new one for me, I've never seen it before, but looks like Anaplan didn't like something about the file format... I have had issues where the file was a CSV.. but there are different kinds of CSV files. For example, when I save data as a CSV in excel, I once picked the "CSV UTF-8" format... and Anaplan rejected it. Since then, I always only use "CSV (Comma Delimited)".