When I went through the features of the CA51 compiler here (8051 Product Selector), I observed that it doesn't have support for CX51/LX51 which offers the extended memory support features which are required by PSoC Creator. So, looks like it isn't compatible and hence the error.
Ok so PSoC Creator only uses LX51 and cannot use BL51? So it's not compatible with CA51, and we need PK51?
Yes, it cannot use BL51. You need to use PK51 license which has all memory support features (CX51/LX51).