While importing the demo data your server configuration may not be enough for the demo data importation.
In that case, you may have to perform a manual demo import.
Below are the steps for the manual demo import.
Step 1: Go to tools >> import >> WordPress import
If the WordPress importer is not installed or activated then install the WordPress importer
here import the content.xml
You will find the file in the WordPress installation folders wp-content >> plugins >> [theme name]-demo-installer >> demo data >> demo
Step 2: install the widget importer & exporter plugin.
then go to tools >> widget importer & exporter
there upload the .wie file if uploading doesn’t work then copy its content and use copy-paste method.
Step 3: Install customizer export/import
then go to appearance >> customize >> export/import
there use/import the .dat file
Step 4: And lastly, import the base theme options
here upload the json file or you can copy paste the content here too
The demo import files are found in your WordPress installation folder's wp-content >> plugins >> [Theme name]-demo-importer >> demo data
and if you can't find them then you can contact us we will provide the files to you