According to the guide you are following you should have something very similiar to this in your httpd.conf.
Code:
<Location /svn/<project>>
DAV svn
SVNPath /srv/svn/<project>
AuthType Basic
AuthName "<project> Repository"
AuthzSVNAccessFile /srv/svn/svn-acl-conf
AuthUserFile /srv/svn/<project>.htpasswd
Require valid-user
</Location>
The block requires a valid user for any access to the /svn/<project> URL. You can enclose the "Require valid-user" statement inside a "Limit" or "LimitExcept" block to control what type of HTTP operations are allowed.
In general for read only access you need to allow GET, PROPFIND, OPTIONS, and REPORT. So we can enclose your "Require" statement inside a "LimitExcept" block.
So you should replace what you have with...
Code:
<Location /svn/<project>>
DAV svn
SVNPath /srv/svn/<project>
AuthType Basic
AuthName "<project> Repository"
AuthzSVNAccessFile /srv/svn/svn-acl-conf
AuthUserFile /srv/svn/<project>.htpasswd
# For any operations other than these, require
# an authenticated user.
<LimitExcept GET PROPFIND OPTIONS REPORT>
Require valid-user
</LimitExcept>
</Location>