Tools: Quartus® Prime Pro Edition
device:-

Since the schematic is not an industry standard format,
The Quartus® Prime Pro Edition symbol block creation function (File menu > Create / Update > Create Symbol Files for Current File) has been removed from the menu since ver.18.0.
There are no plans to support it in the future.

Therefore, either recreate it in a standard language design such as VHDL or Verilog HDL, or
or,
As described in the FAQ (FPGA Knowledge Base) below, please create a .bsf in a version prior to Pro Edition 18.0 and use it.

For more information, please refer to the FAQ below.
Why is the 'Create Symbol Files for Current File' option not available in the Intel® Quartus® Prime Pro Edition software version 18.0?