If the .mx file is well-formed, then the Get function will read in the definition of allBCSkLGdat (I'm assuming that DumpSave was used to create the file). You could try the following to see what was added to the Global namespace (after you execute the Get).

Names["Global`*"]

You could also try

Information[allBCSkLGdat]

(or try Information on whatever else was added to Global) to see its definitions.

But based on the README on the GitHub repo you linked to, I think your best bet would be to reach out using the email or WeChat contact info listed under Communications.