I see. Something that would need to be double checked, but in principle (in case you really have no option to access an aiida and aiida-pseudo installation) you should be able to download the SSSP PPs from the MaterialsCloud and install the files via aiida-pseudo, as you would also do with any other external PP family that isn’t supported by aiida-pseudo per default. I’m referring to the following: How-To Guides — aiida-pseudo 1.5.0 documentation
However, as pointed out by @sphuber in another post Configure Aiida to use remote HPC - #39 by sphuber, the archives that you manually download from MaterialsCloud wouldn’t be compatible with aiida-pseudo install sssp --from-download. So you would need to follow the aforementioned approach (if this would work). Moreover, you wouldn’t directly install the recommended cutoffs.
Maybe @sphuber has something to add on how to circumvent this, in case I missed something.