I cannot reproduce this error. That potential file works fine for me. I suspect you corrupted the format when you downloaded the potential file. Please make sure that you do a “real download” (often this is done via a right click on the link and using “save link as…”) and not cut-n-paste the file into a text editor.
with the latter you may corrupt the format or copy non-ASCII characters (since web browsers often replace ASCII characters with similar looking non-ASCII versions for better readability of the text). LAMMPS requires ASCII encoding and a perfect match of the documented file format.
No.