Error in executing main91 of pythia example

Upon error-free compilation, when I am trying to run the code in Pythia example folder, I am encountering the following error,

error while loading shared libraries: cannot open shared object file: No such file or directory

The shared library is present inside the root lib folder but still it cannot find it. So, how can this error be resolved ?

ROOT Version: 6.20/08
Platform: Ubuntu 20.04.3
Compiler: gcc 9.4.0
Pythia version: 8307

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