The following Oracle Clients are supported by Toad for Oracle 14.1:
Oracle Client or Instant Client 10.2.0.5
Oracle Client or Instant Client 11.2.0.1/11.2.0.3
Oracle Client or Instant Client 12c Release 1 and 2
Oracle Client or Instant Client 18c
Oracle Client or Instant Client 19c
Note: You must use the 32-bit version of Toad with the 32-bit Oracle client, and the 64-bit version of Toad with the 64-bit Oracle client.