Cannot install SP Page Builder Pro

I just installed a clean Joomla 4.1.2 on NameCheap Shared Hosting via Softaculous.

The first thing I did was to go install some Joomshaper extensions and themes.

• I installed the Helix Ultimate Plugin 2.0.7 ok.
• I installed the Politicas 2.0.0 template fine

When I tried to install the SP Page Builder Pro 3.8.6 extension, I got a pink error box with no message.
When I tried to I installed the Helix Ultimate 2.0.7 template I got the same pink messageless error box.

There are no log files in the "/administrator/logs" directory.

I do have a "The PHP temporary folder is not set." warning but in "System Information | Configuration File" the temp path is set to "/home/yada/yada/webroot/tmp", and the path specified is correct. Also in the Folder Permissions tab that path is "writable".

Update:
I created a php.ini file in the web root and added these lines...

; Whether to allow HTTP file uploads.
; http://php.net/file-uploads
file_uploads = On

; Temporary directory for HTTP uploaded files (will use system default if not
; specified).
; http://php.net/upload-tmp-dir
upload_tmp_dir = "/home/yada/yada/webroot/tmp"

; Maximum allowed size for uploaded files.
; http://php.net/upload-max-filesize
upload_max_filesize = 25M

; Maximum number of files that can be uploaded via a single request
max_file_uploads = 20

; Maximum size of POST data that PHP will accept.
; Its value may be 0 to disable the limit. It is ignored if POST data reading
; is disabled through enable_post_data_reading.
; http://php.net/post-max-size
post_max_size = 25M

I made the max filesizes a little on the big side just trying to get things working. The "The PHP temporary folder is not set." warning is gone, but the SP Page Builder Pro extension and Helix template still won't install