Hi Everyone.
I was having the same issue, downloading started again and again when it reached 70 or 90%. That’s how I was able to fix it in UE5.3.
Luckily, I have another UE project file just for checking MetaHuman and I downloaded one random actor before the problem, Importing Metahuman asks for enabling some plugins I enabled for that project. I downloaded my custom metahuman and then migrated the metahuman folder to the main project file. As expected, it asked for enabling some plugins and it worked well.