1、 install svn on my mac.

(master): brew search svn
==> Formulae
colorsvn                                                               git-svn-abandon                                                        svn
==> Casks
smartsvn                                             smartsvn                                             svnx                                                 svnx

(master): brew install svn

2、check the wordpress plugin’s revision number. We want the latest one.

(master) svn log -l 1 https://plugins.svn.wordpress.org/ipanorama-360-virtual-tour-builder-lite/
------------------------------------------------------------------------
r2379956 | avirtum | 2020-09-12 14:17:19 +0800 (Sat, 12 Sep 2020) | 1 line

v.1.6.4
---------------------------------------------------------------------

3、Clone the repo to local directory.

git svn clone --no-minimize-url -s -r2379956 https://plugins.svn.wordpress.org/ipanorama-360-virtual-tour-builder-lite/

...
     A       includes/list-table-items.php
        A       includes/modal-icons.php
        A       includes/page-items.php
        A       languages/ipanorama.pot
        A       readme.txt
r2379956 = c47ebb294916640b8707a6535f9b5e3302927137 (refs/remotes/origin/trunk)
Checked out HEAD:
  https://plugins.svn.wordpress.org/ipanorama-360-virtual-tour-builder-lite/trunk r2379956

4、run fetch process.

(master) ✗ cd ipanorama-360-virtual-tour-builder-lite 

(master) ✗ GIT_TRACE=1 git svn fetch

12:19:46.981872 git.c:670               trace: exec: git-svn fetch
12:19:46.982368 run-command.c:643       trace: run_command: git-svn fetch
04:19:47.223327 git.c:419               trace: built-in: git rev-parse --git-dir
04:19:47.230340 git.c:419               trace: built-in: git rev-parse --show-cdup
04:19:47.237807 git.c:419               trace: built-in: git config --get svn.ignorerefs
04:19:47.242804 git.c:419               trace: built-in: git config --bool --get svn.noauthcache
04:19:47.247764 git.c:419               trace: built-in: git config --bool --get svn.nocheckout
04:19:47.255735 git.c:419               trace: built-in: git config --bool --get svn.parent
...

5、 add the repo into Sourcetree.

Open sourcetree and choose from menu Add Existing Local Repository.

Done.