Sorry, this looks like a new bug introduced on Sept 10 (so my “latest” version was actually a few days out of date when I checked this). Bad timing!
I’ll follow up, but for a quick fix for your data replace seq(1) with just seq on that line.
In terms of steps, at this stage literally just “Create Job”, choose “MRS Data”, select the P-file, “Create Job”, then load. That’s sufficient to check that the basic data import works; of course for the eventual analysis you would also want to include the structural T1, maybe choose the basis set etc – but those aren’t needed until the later steps.