This is not appropriate for Devforum as its not related to Roblox in any way (its technical issues so we can’t do anything about it, sorry ). Blender is not owned or partnered with Roblox and as such you should seek help if you are suffering issues from the Blender manual / help services.
Your issue doesn’t look like its even coming from Roblox files itself (as such its unlikely this forum can give you accurate support).
Yes, but the issue isn’t something to do with Roblox technically. If its failing to open its very unlikely going to be the rig itself, but either as @ImTheTopHat said a file being too big or something else. You’d be better searching google to see if they have methods to get it to open on Blender.
And as we aren’t engineers for Blender, we can’t give you guidance. Sorry if this is coming across as hostile.
Thank you for your imput, I’ve searched google and it comes to developer fourm threads unrelated to the specific topic, I might post on stackexchange for blender.