What's the difference between these two german sentences?

Hi, Im in highschool and I study German as a second language but not many classmates share my interest and enthusiasm :) We havent talked about Subjun

Hi, I'm in highschool and I study German as a second language but not many classmates share my interest and enthusiasm :) We haven't talked about Subjunctive II yet in class, but I've read some articles in the web and I kinda have an idea of it. Recently I came across this sentence in a game I play in German:
Er müsste hier entlanggekommen sein.
I've read that when talking about the past with a subjunctive mood, the helping verb is always hätten even if the main verb uses sein to form the perfect tense and that sein at the end is confusing to me. Is this even correct? If it is, then what would be the difference between that and "Er hätte hier entlanggekommen müssen"? How would they translate in English?

or:Hi, I'm in highschool and I study German as a second language but not many classmates share my interest and enthusiasm :) We haven't talked about Subjunctive II yet in class, but I've read some articles in the web and I kinda have an idea of it. Recently I came across this sentence in a game I play in German:Er m\u00fcsste hier entlanggekommen sein.I've read that when talking about the past with a subjunctive mood, the helping verb is always h\u00e4tten even if the main verb uses sein to form the perfect tense and that sein at the end is confusing to me. Is this even correct? If it is, then what would be the difference between that and \"Er h\u00e4tte hier entlanggekommen m\u00fcssen\"? How would they translate in English?

or:You're right. \"H\u00e4tten\" is normally used for Subjunktiv 2.Er m\u00fcsste hier entlanggekommen sein. = \"Er h\u00e4tte hier entlanggekommen (sein) m\u00fcssen\". Those two sentences have the exact same meaning.m\u00fcsste = h\u00e4tte m\u00fcssen(so here you can see that there are two ways to make the subjunctive form)P.S. I'm a German native speaker..so whenever you have a question, don't hesitate to ask me!

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