[EDIT: see next comment, I was just trying to help here, but maybe wasn’t hastily looking into this.] There are many similar questions, I think this is a Windows-only problem (I can’t replicate on Linux) and this may be helpful:
IJulia install issue - #15 by derekmahar and MbedTLS 1.0.2 failed to load on Julia 1.5.2 (solved by downgrading to MbedTLS 0.7.0) and IJulia install stops for MbedTLS error