Deprecation of the 32-bit Windows DLP Endpoint Agent was announced in 15.8 MP1 and removed in DLP 16.0. The final GA version of the 32-bit Windows DLP Endpoint Agent was 15.8 MP3. There is no 16.0 DLP Endpoint Agent for 32-bit Windows systems.
Symantec Data Loss Prevention 15.8 Maintenance Pack 1 Release Notes
Removed and Deprecated Platforms and Features in Data Loss Prevention 16.0
Release : DLP 16.0
Replace 32-bit Windows Endpoints with 64-bit Windows Endpoints to be able to use the 16.0 DLP Endpoint agent on those systems.