The ppsspp repository is quite large, so a full (shallow or not) clone may exhibit issues due to the amount of submodules and data transferred. If you already have the emulator installed, then there's no point in re-installing it, otherwise try again later on - there's a Github/connection issue and not a RetroPie problem.
Contributions to the project are always appreciated, so if you would like to support us with a donation you can do so here.
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