Onload on the Alveo X3522 requires a compatible net driver version from https://www.xilinx.com/products/boards-and-kits/alveo/x3.html#software such as v1.5.2.0 at the time of writing. Older kernels such as on RHEL 7.9 and RHEL 8.4 also require the auxiliary bus driver to be installed (available from the same download page). See Alveo X3522 Release Notes and documentation.