Looks like upstream rotated or deleted the archive?
[00:00:03] => ncurses-6.2-20210626.tgz doesn't seem to exist in /portdistfiles/ncurses.
[00:00:03] => Attempting to fetch ftp://ftp.invisible-island.net/ncurses/current/ncurses-6.2-20210626.tgz
[00:00:04] fetch: ftp://ftp.invisible-island.net/ncurses/current/ncurses-6.2-20210626.tgz: File unavailable (e.g., file not found, no access)
[00:00:04] => Attempting to fetch https://invisible-mirror.net/archives/ncurses/current/ncurses-6.2-20210626.tgz
[00:00:04] fetch: https://invisible-mirror.net/archives/ncurses/current/ncurses-6.2-20210626.tgz: Not Found
[00:00:04] => Attempting to fetch http://distcache.FreeBSD.org/ports-distfiles/ncurses/ncurses-6.2-20210626.tgz
[00:00:04] fetch: http://distcache.FreeBSD.org/ports-distfiles/ncurses/ncurses-6.2-20210626.tgz: Not Found
[00:00:04] => Couldn't fetch it - please try to retrieve this
[00:00:04] => port manually into /portdistfiles/ncurses and try again.
[00:00:04] *** Error code 1
*** This bug has been marked as a duplicate of bug 259469 ***