APA 7th Edition recommends the following suggestions:

Missing Elements

If the journal does not use volume, issue, and/or article or page numbers, omit the missing element(s) from the reference.

Missing page or article number 

Reference List Example:

Butler, J. (2017). Where access meets multimodality: The case of ASL music videos. Kairos: A Journal of Rhetoric,

Technology, and Pedagogy, 21(1). http://technorhetoric.net/21.1/topoi/butler/index.html

Missing page or article number 

In-text Citation Example:

• To directly quote from written material that does not contain page numbers (e.g., webpages and websites, some ebooks), provide readers with another way of locating the quoted passage any of the following approaches is acceptable; use the approach that will best help readers find the quotation.

• Provide a heading or section name. It is okay to abbreviate a long or unwieldy heading or section name.

• Provide a paragraph number (count the paragraphs manually if they are not numbered).

• Provide a heading or section name in combination with a paragraph number.
   

Link to APA Style Website

• Missing Reference Information