Claws Plugin compilation failure

[Branta]

I use Claws 3.7.3.

I dl'd the Notification plugin from http://www.claws-mail.org/plugins.php
The Install file says:

./configure
make
make install
procedure. The plugin gets installed into
/usr/local/lib/claws-mail/plugins/

From ~/Downloads either $ .configure or sudo ./confure I get this error:

checking pkg-config is at least version 0.9.0... yes
checking for CLAWS_MAIL... configure: error: Package requirements (claws-mail >= 3.7.1.60) were not met:

No package 'claws-mail' found

. . . so make reports:

make: *** No targets specified and no makefile found. Stop

What do I do?


---
Bob