Infinite elements are very hard to use, so I would suggest now:
use LS-Dyna for this, it is the standard (explicit) for wave propagation FE analysis.
In there you can use the keyword manager (beta in 2023 R1) and define a BOUNDARY_NON_REFLECTING keyword to absorb the waves (works well). For this keyword one just needs to choose the 4 faces on the edge/perimeter of the plate, and the correct unit system, so very easy to use (see below).
All the best