https://powerofus.force.com/s/article/NPSP-Install

The recommended method to install NPSP in an existing Salesforce org is to use the NPSP Installer page. This installer simplifies the process by guiding users through the necessary steps and ensuring that all components are correctly installed.

Steps:

Navigate to the NPSP Installer page on Salesforce.org.

Click the "Install NPSP" button to start the installation process.

Follow the prompts to authenticate and select the Salesforce org where NPSP will be installed.

The installer will automatically download and configure all required NPSP components.

Verify the installation by checking the NPSP settings and ensuring all components are functional.